Carbohydrates have been implicated in many physiologically important cell surface functions including cell-cell recognition, growth control and receptors for toxins, glycoprotein hormones and interferon. The difficulties in obtaiing sufficient amounts and determining the structure of the limited quantities of physiologically important cell surface oligosaccharides are major reasons for the lack of knowledge about what specific sugar structures are involved in these processes. Fortunately, the free oligosaccharides of human milk contain many sugar sequences also found in glycolipids and glycoproteins. When coupled to polypeptides the oligosaccharides become effective immunogens and produce antibodies that can be used in sensitive radioimmunoassays to detect and measure specific carbohydrate structures in complex biological samples. Abnormal oligosaccharides are diagnostic for certain diseases and genetic disorders of their metabolism. Structural analyses of these sugars require laborious purification and expensive instruments; chemical methods, therefore, are generally not applicable to possible screening, diagnosis or classification of these diseases. Radioimmunoassays for diagnostically important oligosaccharides may be a valuable alternative. As a basis for this application of anti-carbohydrate antibodies, specific antisera against human sialyloligosaccharide structures will be applied to the analysis of gangliosides from human meconium, a potential diagnostic specimen and a rich source of extra-neural, fetal glycolipids and glycoproteins. Whether cell surface oligosaccharide changes associated with malignant transformation are related to turmorigenicity is unknown, because their functions are unknown. Existing methods have failed to associate specific cell surface carbohydrate structures with their proposed receptor function; GM1, a common ganglioside that binds cholera toxin, is the exception. Functional oligosaccharides may be present on cell surfaces in quantities below current detection limits. Radioimmune-binding techniques using physiologically important carbohydrate-binding proteins will be applied to the isolation and characterization of corresponding sugar ligands for cholera toxin and other protein agonists that bind carbohydrate receptors.